Club
Certificate
2024

Boat

Northern Harrier

CAN 84185

Portsmouth Olympic Harbour
53 Yonge Street
Kingston, Ontario
Canada K7M 6G4
Rated boat velocities in knots
Wind Velocity6 kt 8 kt 10 kt 12 kt 14 kt 16 kt 20 kt 24 kt
Beat Angles42.1°40.0°37.6°36.6°36.2°35.9°35.7°36.2°
Beat VMG3.954.725.195.395.505.565.645.62
52°5.966.827.227.427.527.587.667.69
60°6.246.997.367.587.697.767.867.91
75°6.397.097.477.737.928.038.218.33
90°6.247.037.457.768.018.238.548.77
110°5.846.947.517.898.248.549.059.49
120°5.686.817.437.868.258.639.4310.40
135°5.136.327.107.587.998.419.4011.16
150°4.335.486.457.137.577.958.769.94
Run VMG3.754.745.606.296.877.358.088.85
Gybe Angles143.7°148.0°152.1°158.1°169.6°177.2°178.1°177.2°
APH ToD:531.5CDL: 9.894APH ToT: 1.1289CertNo:ON2427
BOAT
ClassJ41DesignerRod JohnstoneBuilderTillotson PearsonAge date05/1985Series date05/1985Offset fileUS17807.OFFData fileCAN84185-Northern Harrier
HULL
Length Overall12.470 mMaximum Beam4.005 mDraft2.225 mDisplacement5,899 kgDLR7.6714IMS DivisionPerformanceDynamic Allowance0.000%Age Allowance0.487%
PROPELLER
InstallationShaft exposedTypeFeathering 2 bladesDiameter0.513m
CREW
Maximum weight980 kg(declared)Minimum weight833 kg * when appliedNon Manual PowerNoCrew Arm Extension0.00 m
SAIL AREAS (m²)
MeasuredRatedMainsail40.5441.23Headsail Luffed56.9556.95Headsail FlyingSymmetric113.44113.44Asymmetric93.0093.00 (All asymmetric spinnakers with SHW/SFL > 85%)
STORM SAIL AREAS (m²)
Trysail11.99Storm Jib12.95Heavy Weather Jib34.96
SAIL LIMITS
Headsails6  Spinnakers5 * Asymmetric may be tacked on the pole
STABILITY
Righting MomentN/AStability IndexN/A
The owner and any other person in charge is responsible that boat is complying with her certificate in accordance with RRS 78.1 and ORC Rule 304.

Club
Certificate
2024

Boat

Northern Harrier

CAN 84185

Portsmouth Olympic Harbour
53 Yonge Street
Kingston, Ontario
Canada K7M 6G4
Time Allowances in secs/NM
Wind Velocity6 kt 8 kt 10 kt 12 kt 14 kt 16 kt 20 kt 24 kt
Beat VMG910.9762.1693.7667.8654.6647.1638.4640.2
52°604.5527.8498.3485.2479.0475.2469.9468.1
60°577.4514.8488.8475.2468.4464.2457.9455.3
75°563.4507.5481.8465.8454.8448.2438.4432.1
90°577.4512.1483.1464.2449.3437.3421.4410.4
110°616.7518.6479.4456.0436.8421.3397.9379.4
120°633.9528.5484.4458.0436.3417.1381.6346.1
135°701.7569.6507.1474.9450.8428.2383.0322.6
150°830.9657.3557.8505.0475.3452.7410.9362.0
Run VMG959.5758.9642.9572.0524.1489.7445.5406.8
Selected Courses
Windward / Leeward935.2760.5668.3619.9589.4568.4542.0523.5
All purpose722.8604.1546.6516.4496.9482.8460.8441.2
Single Number Scoring Options
CourseTime On
Distance
Time On
Time
Windward / Leeward644.30.9313
All purpose531.51.1289
 
Custom scoring options for Australia
Scoring OptionTime On
Distance
Time On
Time
Triple Number Coastal/Long Distance Low663.40.9044
Triple Number Coastal/Long Distance Medium528.91.1344
Triple Number Coastal/Long Distance High478.01.2551
Triple Number Windward/Leeward Low847.80.7077
Triple Number Windward/Leeward Medium640.10.9373
Triple Number Windward/Leeward High563.71.0644
Custom scoring options for Austria
Scoring OptionTime On
Distance
Time On
Time
Coastal/Long Distance575.91.0418
Triple Number Coastal/Long Distance Low663.40.9044
Triple Number Coastal/Long Distance Medium528.91.1344
Triple Number Coastal/Long Distance High478.01.2551
Triple Number Windward/Leeward Low847.80.7077
Triple Number Windward/Leeward Medium640.10.9373
Triple Number Windward/Leeward High563.71.0644
Performance Curve6 kt 8 kt 10 kt 12 kt 14 kt 16 kt 20 kt 24 kt
Coastal/Long Distance937.6719.0608.9548.3514.9488.1443.6423.3
Custom scoring options for Brazil
Scoring OptionTime On
Time
Upwind "bolina"0.8443
Downwind "popa"0.9561
70% up, 30% down "Ilhabela"0.8750
30% up, 70% down "Ilhabela-inverso"0.9196
Custom scoring options for Bulgaria
Scoring OptionTime On
Distance
Time On
Time
Triple Number Coastal/Long Distance Low663.40.9044
Triple Number Coastal/Long Distance Medium528.91.1344
Triple Number Coastal/Long Distance High478.01.2551
Triple Number Windward/Leeward Low847.80.7077
Triple Number Windward/Leeward Medium640.10.9373
Triple Number Windward/Leeward High563.71.0644
Predominantly Upwind566.91.0584
Predominantly Downwind544.91.1012
Custom scoring options for Canada
Scoring OptionTODTOT
Triple Number AP Low663.40.9044
Triple Number AP Medium529.01.1343
Triple Number AP High478.11.2551
Triple Number Windward/Leeward Low847.80.7077
Triple Number Windward/Leeward Medium640.10.9373
Triple Number Windward/Leeward High563.71.0644
Single Number Predominant Upwind565.31.0613
Single Number Predominant Reaching512.51.1707
Single Number Predominant Downwind545.81.0993
Predominant Upwind - Low711.70.8431
Predominant Upwind - Low/Med610.40.9829
Predominant Upwind - Medium552.11.0867
Predominant Upwind - Med/High521.91.1497
Predominant Upwind - High505.71.1864
Predominant Downwind Low740.00.8108
Predominant Downwind Low/Med611.20.9816
Predominant Downwind Medium528.11.1361
Predominant Downwind Med/High474.11.2656
Predominant Downwind High438.51.3683
Predominant Reaching Low650.80.9219
Predominant Reaching Low/Med557.81.0756
Predominant Reaching Medium500.61.1986
Predominant Reaching Med/High463.81.2935
Predominant Reaching High438.61.3680
SA/DSPL Upwind29.68SA/DSPL Downwind46.88
Scoring OptionTODTOT
5-Band Windward/Leeward Low895.50.6700
5-Band Windward/Leeward Low/Med733.00.8186
5-Band Windward/Leeward Medium630.20.9521
5-Band Windward/Leeward Med/High571.81.0493
5-Band Windward/Leeward High543.31.1043
Windward/Leeward 60-40 Low891.90.6728
Windward/Leeward 60-40 Low/Med735.60.8157
Windward/Leeward 60-40 Medium639.30.9385
Windward/Leeward 60-40 Med/High587.21.0218
Windward/Leeward 60-40 High562.71.0663
5-Band AP Low695.80.8623
5-Band AP Low/Med588.41.0198
5-Band AP Medium522.61.1481
5-Band AP Med/High484.31.2390
5-Band AP High461.21.3009
5-Band SF Bay Tour - Low848.50.7071
5-Band SF Bay Tour - Low/Med700.10.8570
5-Band SF Bay Tour - Medium609.10.9851
5-Band SF Bay Tour - Med/High558.71.0739
5-Band SF Bay Tour - High531.71.1284
Chicago-Mac Upwind1.0423
Chicago-Mac All Purpose1.0598
Chicago-Mac Downwind1.0829
Bayview-Mac Cove Island0.9968
Bayview-Mac Shore1.0086
Harvest Moon Regatta470.11.2764
Custom scoring options for Cyprus
Scoring OptionTime On
Distance
Time On
Time
Coastal/Long Distance575.91.0418
Triple Number Coastal/Long Distance Low663.40.9044
Triple Number Coastal/Long Distance Medium528.91.1344
Triple Number Coastal/Long Distance High478.01.2551
Triple Number Windward/Leeward Low847.80.7077
Triple Number Windward/Leeward Medium640.10.9373
Triple Number Windward/Leeward High563.71.0644
Performance Curve6 kt 8 kt 10 kt 12 kt 14 kt 16 kt 20 kt 24 kt
Coastal/Long Distance937.6719.0608.9548.3514.9488.1443.6423.3
Custom scoring options for Denmark
Scoring OptionTime On
Distance
Time On
Time
Coastal/Long Distance575.91.0418
Triple Number Coastal/Long Distance Low663.40.9044
Triple Number Coastal/Long Distance Medium528.91.1344
Triple Number Coastal/Long Distance High478.01.2551
Triple Number Windward/Leeward Low847.80.7077
Triple Number Windward/Leeward Medium640.10.9373
Triple Number Windward/Leeward High563.71.0644
Performance Curve6 kt 8 kt 10 kt 12 kt 14 kt 16 kt 20 kt 24 kt
Coastal/Long Distance937.6719.0608.9548.3514.9488.1443.6423.3
Custom scoring options for Spain
Scoring OptionTime On
Distance
Coastal/Long Distance575.9
Performance Curve6 kt 8 kt 10 kt 12 kt 14 kt 16 kt 20 kt 24 kt
Coastal/Long Distance937.6719.0608.9548.3514.9488.1443.6423.3
Custom scoring options for Estonia
Scoring OptionTime On
Distance
Time On
Time
Triple Number Coastal/Long Distance Low663.40.9044
Triple Number Coastal/Long Distance Medium528.91.1344
Triple Number Coastal/Long Distance High478.01.2551
Triple Number Windward/Leeward Low847.80.7077
Triple Number Windward/Leeward Medium640.10.9373
Triple Number Windward/Leeward High563.71.0644
Custom scoring options for Finland
Scoring OptionTime On
Distance
Time On
Time
FinRating (Coastal/Long Distance)575.91.0418
Triple Number Coastal/Long Distance Low663.40.9044
Triple Number Coastal/Long Distance Medium528.91.1344
Triple Number Coastal/Long Distance High478.01.2551
Triple Number Windward/Leeward Low847.80.7077
Triple Number Windward/Leeward Medium640.10.9373
Triple Number Windward/Leeward High563.71.0644
Performance Curve6 kt 8 kt 10 kt 12 kt 14 kt 16 kt 20 kt 24 kt
Coastal/Long Distance937.6719.0608.9548.3514.9488.1443.6423.3
Custom scoring options for France
Scoring OptionTime On
Distance
Time On
Time
Triple Number Coastal/Long Distance Low663.40.9044
Triple Number Coastal/Long Distance Medium528.91.1344
Triple Number Coastal/Long Distance High478.01.2551
Triple Number Windward/Leeward Low847.80.7077
Triple Number Windward/Leeward Medium640.10.9373
Triple Number Windward/Leeward High563.71.0644
Custom scoring options for Germany
Scoring OptionTime On
Time
Triple Number Coastal/Long Distance Low0.9044
Triple Number Coastal/Long Distance Medium1.1344
Triple Number Coastal/Long Distance High1.2551
Triple Number Windward/Leeward Low0.7077
Triple Number Windward/Leeward Medium0.9373
Triple Number Windward/Leeward High1.0644
Performance Curve6 kt 8 kt 10 kt 12 kt 14 kt 16 kt 20 kt 24 kt
Coastal/Long Distance937.6719.0608.9548.3514.9488.1443.6423.3
Custom scoring options for Greece
Scoring OptionTime On
Distance
Time On
Time
Coastal/Long Distance575.91.0418
Triple Number Coastal/Long Distance Low663.40.9044
Triple Number Coastal/Long Distance Medium528.91.1344
Triple Number Coastal/Long Distance High478.01.2551
Triple Number Windward/Leeward Low847.80.7077
Triple Number Windward/Leeward Medium640.10.9373
Triple Number Windward/Leeward High563.71.0644
Performance Curve6 kt 8 kt 10 kt 12 kt 14 kt 16 kt 20 kt 24 kt
Coastal/Long Distance937.6719.0608.9548.3514.9488.1443.6423.3
Custom scoring options for Hungary
Scoring OptionTime On
Distance
Time On
Time
Triple Number Coastal/Long Distance Low663.40.9044
Triple Number Coastal/Long Distance Medium528.91.1344
Triple Number Coastal/Long Distance High478.01.2551
Triple Number Windward/Leeward Low847.80.7077
Triple Number Windward/Leeward Medium640.10.9373
Triple Number Windward/Leeward High563.71.0644
Custom scoring options for Israel
Scoring OptionTime On
Distance
Time On
Time
Coastal/Long Distance575.91.0418
Triple Number Coastal/Long Distance Low663.40.9044
Triple Number Coastal/Long Distance Medium528.91.1344
Triple Number Coastal/Long Distance High478.01.2551
Triple Number Windward/Leeward Low847.80.7077
Triple Number Windward/Leeward Medium640.10.9373
Triple Number Windward/Leeward High563.71.0644
Performance Curve6 kt 8 kt 10 kt 12 kt 14 kt 16 kt 20 kt 24 kt
Coastal/Long Distance937.6719.0608.9548.3514.9488.1443.6423.3
Custom scoring options for Japan
Scoring OptionTime On
Distance
Time On
Time
Coastal/Long Distance575.91.0418
Triple Number Coastal/Long Distance Low663.40.9044
Triple Number Coastal/Long Distance Medium528.91.1344
Triple Number Coastal/Long Distance High478.01.2551
Triple Number Windward/Leeward Low847.80.7077
Triple Number Windward/Leeward Medium640.10.9373
Triple Number Windward/Leeward High563.71.0644
Performance Curve6 kt 8 kt 10 kt 12 kt 14 kt 16 kt 20 kt 24 kt
Coastal/Long Distance937.6719.0608.9548.3514.9488.1443.6423.3
Custom scoring options for Korea
Scoring OptionTime On
Distance
Triple Number Coastal/Long Distance Low663.4
Triple Number Coastal/Long Distance Medium528.9
Triple Number Coastal/Long Distance High478.0
Triple Number Windward/Leeward Low847.8
Triple Number Windward/Leeward Medium640.1
Triple Number Windward/Leeward High563.7
Predominantly Upwind566.9
Predominantly Downwind544.9
Predominantly Reaching522.0
Custom scoring options for Lithuania
Scoring OptionTime On
Distance
Time On
Time
Coastal/Long Distance575.91.0418
Triple Number Coastal/Long Distance Low663.40.9044
Triple Number Coastal/Long Distance Medium528.91.1344
Triple Number Coastal/Long Distance High478.01.2551
Triple Number Windward/Leeward Low847.80.7077
Triple Number Windward/Leeward Medium640.10.9373
Triple Number Windward/Leeward High563.71.0644
Performance Curve6 kt 8 kt 10 kt 12 kt 14 kt 16 kt 20 kt 24 kt
Coastal/Long Distance937.6719.0608.9548.3514.9488.1443.6423.3
Custom scoring options for Netherlands
Scoring OptionTime On
Time
Triple Number Coastal/Long Distance Low0.9044
Triple Number Coastal/Long Distance Medium1.1344
Triple Number Coastal/Long Distance High1.2551
Triple Number Windward/Leeward Low0.7077
Triple Number Windward/Leeward Medium0.9373
Triple Number Windward/Leeward High1.0644
Coastal/Long Distance1.0418
Predominantly Upwind1.0584
Predominantly Downwind1.1012
For information
General Purpose Handicap (GPH)592.1
Custom scoring options for Norway
Scoring OptionTime On
Time
Tretall Distanseseilas Lite vind0.9044
Tretall Distanseseilas Mellomvind1.1344
Tretall Distanseseilas Mye vind1.2551
Tretall Pølsebane Lite vind0.7077
Tretall Pølsebane Mellomvind0.9373
Tretall Pølsebane Mye vind1.0644
Distanseseilas ett tall1.1289
Enkeltall Motvind1.0584
Enkeltall Medvind1.1012
Custom scoring options for Portugal
Scoring OptionTime On
Distance
Time On
Time
Triple Number Coastal/Long Distance Low663.40.9044
Triple Number Coastal/Long Distance Medium528.91.1344
Triple Number Coastal/Long Distance High478.01.2551
Triple Number Windward/Leeward Low847.80.7077
Triple Number Windward/Leeward Medium640.10.9373
Triple Number Windward/Leeward High563.71.0644
Coastal/Long Distance575.91.0418
Custom scoring options for Russia
Scoring OptionTime On
Distance
Time On
Time
Predominantly Upwind566.91.0584
Predominantly Downwind544.91.1012
Custom scoring options for South Africa
Scoring OptionTime On
Distance
Time On
Time
Cape Doctor Inshore529.01.1341
Cape Doctor Coastal447.11.3420
Triple Number Coastal/Long Distance Low663.40.9044
Triple Number Coastal/Long Distance Medium528.91.1344
Triple Number Coastal/Long Distance High478.01.2551
Triple Number Windward/Leeward Low847.80.7077
Triple Number Windward/Leeward Medium640.10.9373
Triple Number Windward/Leeward High563.71.0644
Custom scoring options for Slovenia
Scoring OptionTime On
Time
Triple Number Coastal/Long Distance Low0.9044
Triple Number Coastal/Long Distance Medium1.1344
Triple Number Coastal/Long Distance High1.2551
Triple Number Windward/Leeward Low0.7077
Triple Number Windward/Leeward Medium0.9373
Triple Number Windward/Leeward High1.0644
Custom scoring options for Switzerland
Scoring OptionTime On
Time
Triple Number Coastal/Long Distance Low0.9044
Triple Number Coastal/Long Distance Medium1.1344
Triple Number Coastal/Long Distance High1.2551
Triple Number Windward/Leeward Low0.7077
Triple Number Windward/Leeward Medium0.9373
Triple Number Windward/Leeward High1.0644
Custom scoring options for Sweden
Scoring OptionTime On
Distance
Time On
Time
Coastal/Long Distance575.91.0418
Triple Number Coastal/Long Distance Low663.40.9044
Triple Number Coastal/Long Distance Medium528.91.1344
Triple Number Coastal/Long Distance High478.01.2551
Triple Number Windward/Leeward Low847.80.7077
Triple Number Windward/Leeward Medium640.10.9373
Triple Number Windward/Leeward High563.71.0644
Predominantly Upwind566.91.0584
Predominantly Downwind544.91.1012
Performance Curve6 kt 8 kt 10 kt 12 kt 14 kt 16 kt 20 kt 24 kt
Coastal/Long Distance937.6719.0608.9548.3514.9488.1443.6423.3
Custom scoring options for Ukraine
Scoring OptionTime On
Distance
Time On
Time
Coastal/Long Distance575.91.0418
Triple Number Coastal/Long Distance Low663.40.9044
Triple Number Coastal/Long Distance Medium528.91.1344
Triple Number Coastal/Long Distance High478.01.2551
Triple Number Windward/Leeward Low847.80.7077
Triple Number Windward/Leeward Medium640.10.9373
Triple Number Windward/Leeward High563.71.0644
Performance Curve6 kt 8 kt 10 kt 12 kt 14 kt 16 kt 20 kt 24 kt
Coastal/Long Distance937.6719.0608.9548.3514.9488.1443.6423.3
Custom scoring options for United States of America
Scoring OptionTODTOT
Triple Number AP Low663.40.9044
Triple Number AP Medium529.01.1343
Triple Number AP High478.11.2551
Triple Number Windward/Leeward Low847.80.7077
Triple Number Windward/Leeward Medium640.10.9373
Triple Number Windward/Leeward High563.71.0644
Single Number Predominant Upwind565.31.0613
Single Number Predominant Reaching512.51.1707
Single Number Predominant Downwind545.81.0993
Predominant Upwind - Low711.70.8431
Predominant Upwind - Low/Med610.40.9829
Predominant Upwind - Medium552.11.0867
Predominant Upwind - Med/High521.91.1497
Predominant Upwind - High505.71.1864
Predominant Downwind Low740.00.8108
Predominant Downwind Low/Med611.20.9816
Predominant Downwind Medium528.11.1361
Predominant Downwind Med/High474.11.2656
Predominant Downwind High438.51.3683
Predominant Reaching Low650.80.9219
Predominant Reaching Low/Med557.81.0756
Predominant Reaching Medium500.61.1986
Predominant Reaching Med/High463.81.2935
Predominant Reaching High438.61.3680
SA/DSPL Upwind29.68SA/DSPL Downwind46.88
Scoring OptionTODTOT
5-Band Windward/Leeward Low895.50.6700
5-Band Windward/Leeward Low/Med733.00.8186
5-Band Windward/Leeward Medium630.20.9521
5-Band Windward/Leeward Med/High571.81.0493
5-Band Windward/Leeward High543.31.1043
Windward/Leeward 60-40 Low891.90.6728
Windward/Leeward 60-40 Low/Med735.60.8157
Windward/Leeward 60-40 Medium639.30.9385
Windward/Leeward 60-40 Med/High587.21.0218
Windward/Leeward 60-40 High562.71.0663
5-Band AP Low695.80.8623
5-Band AP Low/Med588.41.0198
5-Band AP Medium522.61.1481
5-Band AP Med/High484.31.2390
5-Band AP High461.21.3009
5-Band SF Bay Tour - Low848.50.7071
5-Band SF Bay Tour - Low/Med700.10.8570
5-Band SF Bay Tour - Medium609.10.9851
5-Band SF Bay Tour - Med/High558.71.0739
5-Band SF Bay Tour - High531.71.1284
Chicago-Mac Upwind1.0423
Chicago-Mac All Purpose1.0598
Chicago-Mac Downwind1.0829
Bayview-Mac Cove Island0.9968
Bayview-Mac Shore1.0086
Harvest Moon Regatta470.11.2764

Club
Certificate
2024

Boat

Northern Harrier

CAN 84185

Portsmouth Olympic Harbour
53 Yonge Street
Kingston, Ontario
Canada K7M 6G4
Data in meters/kilograms (Metric)
HULL AND APPENDAGES (Lightship Trim)
ClassJ41Measurement23/05/1989HINPlan reviewHull constructionLightCarbon RudderNoLight stanchionsNoTrim tabNo
LOA12.470Max. Beam4.005Draft2.225Displacement5,899Wetted area26.43IMS L9.787LSM09.161Acc. length12.470Sink (kg/mm) 19.42
VCGD-0.041VCGM0.011RM Rated (kg·m) 152.8Limit of positive stability(°) N/AStability IndexN/ADefault crew weight607Declared crew weight980
PROPELLER
Propeller TypeFeathering 2 blades
InstallationShaft exposedTwin screwNoHydro generatorNo
PRD0.513PBW0.153PIPA0.0063
PSD0.031PHD0.068PHL0.110
PSA25.0°ESL0.778
ST10.028ST20.116ST30.122
ST40.068ST50.196
RIG
Forestay tensionAftInner stayAdjustableMast materialAluminumSingle headsail furlerNoMainsail furlerNoArticulated bowspritNoNon-circular riggingNoFiber riggingNoAdjustable mast footNoRunners/Checkstays2Spreaders3Rotating mastNo
P14.402IG16.012ISP16.280MDT10.113MDL10.180MDT20.113MDL20.180TL0.000MW0.185GO0.208
E4.755J4.694BAS1.634FSD0.022SFJ0.000SPL4.788WPLTPSBD0.202MWT0.00MCG0.000
Flying Headsail Foretriangles IdISPTPS
FLOTATION AND STABILITY
Calculation methodRM estimatedFlotation Date23/05/1989
BALLAST
TANKS
INVENTORY
INVENTORY
Fixed Ballast Total0
Total deductible
Total deductible

Club
Certificate
2024

Boat

Northern Harrier

CAN 84185

Portsmouth Olympic Harbour
53 Yonge Street
Kingston, Ontario
Canada K7M 6G4
MAINSAIL
IdMHBMUWMTWMHWMQWAreaMeas.DateCommentMN-A0.180.961.733.024.0440.5425/03/2024Main 2+3
HEADSAIL
IdHHBHUWHTWHHWHQWHLPHLUBtnFlyingFTAreaMeas.DateCommentJ1-A0.060.851.683.525.417.2815.93NoNo 56.9529/03/2024
SYMMETRIC SPINNAKER
IdSLUSLESLSHWSFLAreaMeas.DateCommentS2-A16.0616.0616.068.508.38113.4412/07/20232023 S2 Blue
ASYMMETRIC SPINNAKER
IdSLUSLESLSHWSFLRatioAreaMeas.DateCommentA1-A16.5015.0615.786.947.6091%93.0025/03/2024A 1.0 Spinnaker